Mild flu could hit harder in the fall -- baltimoresun.com

Mild flu could hit harder in the fall -- baltimoresun.com: "The number of swine flu cases in Mexico is stabilizing. In the U.S., though more people are being diagnosed with the virus, cases have been mostly mild, claiming two lives. And health officials have backed off on closing schools where students are sick.

It may seem as though the threat of the virus known as H1N1 has lessened. But infectious disease experts and public health officials agree: The worst is likely still to come. In pandemics of the past, flu that arrived in the spring hit harder come fall, when influenza season returned.

'If you were just to bet on the odds, you would bet H1N1 would abate in the summer and return in the winter,' said Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University School of Medicine in Tennessee.

'The illness produced, so far, is really quite mild. But the question would be - as it circulates among humans in the Southern Hemisphere [in their winter flu season] - could it pick up a virulence gene ... that is capable of producing severe disease?"